農藝系副教授聯手國內外農業試驗單位 解密氣候變遷對水稻抗褐飛蝨基因之影響
在氣候變遷影響下，如何實現環境永續，篩選作物抗性品種一直是全球育種家的目標。台大農藝系副教授莊汶博團隊與行政院農委會桃園區農業改良場、農業試驗所及國際水稻研究所（International Rice Research Institute, IRRI），共同解密環境變化對水稻抗褐飛蝨基因之影響，提供水稻育種家未來抗蟲育種的重要參考依據。
根據聯合國政府間氣候變遷委員會（Intergovernmental Panel on Climate Change, IPCC）預測，大氣溫度會在西元2030年前至少升溫1.5℃，西元2050年以前至少升溫2℃，極端氣候發生率增加，作物病蟲害發生頻仍，導致糧食作物產量及品質下降。
為實現環境永續，篩選作物抗性品種一直是全球育種家的目標，以期在不減少糧食產量前提下減少殺蟲劑使用。褐飛蝨（Nilaparvata lugens Stål）<a href="https://www.noktashop.org">sex shop</a> 為亞洲主要水稻害蟲，藉由吸食水稻韌皮部汁液，不僅在植物表面留下致命灼傷（hooper burn），更使職務在被吸食過程中感染致命的草狀矮縮病毒（grassy stunt virus）及齒葉矮縮病毒（ragged stunt virus），嚴重危害全球水稻產區經濟產值。
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褐飛蝨。
近幾十年來，市場上各式水稻品系中已發現超過30種抗褐飛蝨基因（BPH-resistant genes），然而，隨著褐飛蝨生物型（biotype）不斷演化，各品系已逐漸降低其對褐飛蝨之抗性，且受制於氣候變遷影響的抗褐飛蝨基因種類及影響機制尚不明，因此莊汶博協同農委會桃園區農業改良場、農業試驗所及國際水稻研究所，共同解密環境變化對水稻抗褐飛蝨基因之影響，期能縮短水稻育種時程。
.JPG "褐飛蝨吸食水稻")
褐飛蝨吸食水稻。
研究團隊利用秧苗期檢定法（Standard Seedbox Screening Test, SSST）評估各種帶抗褐飛蝨基因之水稻近源品系（near-isogenic lines, NILs），在三種模擬現今、西元2050年及西元2100年預測之氣溫及二氧化碳濃度的環境下，分別進行各品系的抗生性（antibiosis）及抗棲性（antixenosis）實驗。
結果顯示，9個帶有單一抗褐飛蝨基因之近源品系中，僅有 NIL-BPH17 及 NIL-BPH20 兩品系不受環境變化影響，而3個帶雙抗褐飛蝨基因之近源品系中，僅有 NIL-BPH18+32、NIL-BPH9+32 兩品系不受環境變化影響。
研究團隊進一步針對單抗蟲基因品系 NIL-BPH17 及 NIL-BPH20 在不同環境下進行抗生性（antibiosis）實驗及抗棲性（antixenosis）實驗，其中抗生性實驗包括褐飛蝨之蜜露排泄物試驗（Honeydew Excretion Test）、族群成長率（Population Growth Rate, PGR）、若蟲存活率（Nymph Survival Rate）及產卵生物測定法（Oviposition Bioassay），結果顯示，褐飛蝨在這兩個近同源系有不同表現：NIL-BPH17 對於褐飛蝨的抑制效應不受環境影響，而當環境改變時 NIL-BPH20 則會喪失其抗性。
此研究結果可作為水稻育種家未來抗蟲育種之重要參考依據，並已於2021年發表於《Rice》。
［Kuang et al. 2021. The impact of climate change on the resistance of rice near-isogenic lines with resistance genes against brown planthopper. Rice 14:64. https://doi.org/10.1186/s12284-021-00508-6］
The Impacts of Climate Change on the Performance of BPH-resistance Gene in Rice
The Intergovernmental Panel on Climate Change (IPCC) predicted that the atmospheric temperature will increase by at least 1.5℃before 2030 and 2℃before 2050. Global warming effects increase the frequency of extreme weather, and cause the environmental stresses leading to high frequency of insect herbivory damage on crop plants. It is also predicted that global warming will enlarge the insect population size to cause substantial crop yield losses. Hence, developing disease- and pest-resistant crop varieties is always important for the breeders in the world. With the view to environmental sustainability, pest-resistant crops have been promised to reduce pesticide usage without yield loss.
Nilaparvata LugensStål (Brown planthopper; BPH) is one of the most destructive rice pests in Asia. By sucking the phloem sap, N. lugens not only damages the crop directly leading to plant mortality symptom called the “hooper burn,” but also transmit the grassy and ragged stunt viruses to the rice plant. Severe rice yield losses have been caused by N. lugens damage.
Brown planthoppers
Over the past decades, more than 30 BPH-resistant genes have been identified in rice. However, N. lugens has multiple biotypes and is prone to gain resistance. The number of BPH-resistant genes required for resistance to N. lugens and the effects of climate change on the mechanisms of pest resistance are still unclear. Associate Prof. Wen-Po Chung at Department of Agronomy cooperated with researchers from Taoyuan District Agricultural Research and Extension Station, Taiwan Agricultural Research Institute, and International Rice Research Institute to reveal the impacts of climate change on the performance of BPH-resistant genes. It is believed that this study will help to shorten the breeding progress of BPH-resistant rice varieties.
Brown planthoppers fed on rice plants
The research team evaluated the antibiotic and antixenosis in rice near-isogenic lines (NILs) carrying BPH-resistant gene under three different environmental conditions, including ambient conditions, conditions at the atmospheric temperature with corresponding carbon dioxide in year 2050 and the year 2100, based on the IPCC prediction. The result indicated that only two NILs (NIL-BPH17 and NIL-BPH20) which carried single BPH-resistant gene and two NILs (NIL-BPH18+32、NIL-BPH9+32) which carried double BPH-resistant genes maintained BPH resistance ability despite environmental changes.
The antibiosis and antixenosis of two NILs (NIL-BPH17 and NIL-BPH20) were further examined under three different environmental conditions. The honeydew excretion, population growth rate, nymph survival rate, and oviposition bioassay were used to evaluate the antibiosis, while the choice test was used to evaluate the antixenosis.
The results showed the inhibitory effect in NIL-BPH17 on the BPH growth and development was unaffected, while NIL-BPH20 may have lost its resistance to BPH when the growth environment changed. In summary, the result provides breeders a valuable information to develop BPH-resistant varieties and the strategy for integrated pest management in the future. This study is published in Rice, 2021. (Kuang et al. 2021. The impact of climate change on the resistance of rice near-isogenic lines with resistance genes against <a href="https://www.escortfly.com/ad-category/sisli-escort">şişli escort</a>brown planthopper. Rice 14:64. https://doi.org/10.1186/s12284-021-00508-6)
